(1) Field of the Invention
The present invention relates to a digital broadcast system and more specifically to a system that provides predetermined services to viewers in accordance with certain broadcasts watched by the viewers.
(2) Description of the Prior Art
Developments in the semiconductor and digital communication technologies have enabled the realization of digital satellite broadcasting. Non-satellite broadcasting via wired or wireless communication is also progressing.
Digital broadcasting allows various types of data, in addition to images and audio data, to be sent to viewers. For instance, scripts that control displays of user-selectable alternatives relating to program content and prompts for viewer selections can be broadcasted with programs to allow user interaction.
Also, with digital broadcasting, viewer management, such as that used for PPV (Pay Per View) services that selectively distribute programs to certain viewers, can be easily and precisely performed. In such services, the host station broadcasts a PPV program which has been encrypted (scrambled), and only viewers who have paid the fee are allowed to set the key information for decrypting (descrambling) in their digital broadcast receiving devices to watch the fee-based program. In most cases, the viewer will order a fee-based program he wishes to watch before the program is broadcasted, and will receive data on which the key information is based from the broadcaster via a telephone line.
This type of conventional digital broadcasting technology is disclosed by Japanese Laid-Open Patent Applications No.8-125624 and No.8-56348.
Patent Application No.8-125624 discloses a technology to compress information relating to phone numbers to which the viewer should send his reply, multiplex it into a broadcast signal, and send the broadcast signal. The viewer can easily participate in an interactive program using a cellular phone that makes replies in accordance with the sent information.
Patent Application No.8-56348 discloses a device into which functions of a remote-control of a digital broadcast receiving device and a cellular phone are integrated. This device makes it easy for the viewer to receive and set information for the descrambling, such as a key.
These conventional technologies can provide viewers with a variety of digital broadcasting services, such as for PPV and interactive programs, and only require the viewer to perform relatively simple operations.
Currently, all kinds of programs are digitally broadcasted using many channels. Like ordinary TV channels, different programs are broadcasted at different times on each channel.
As things stand, users have to perform complex operations to inform the broadcaster of the fee-based program they want to watch. For instance, when a viewer who is watching a program at no charge wishes to watch a scrambled fee-based program that follows the free program on the same channel, the viewer has to search through a vast amount of information for numerous programs to find the channel number, the broadcast starting time, or the code number which specifies the fee-based program, before sending the information to the broadcaster via a cellular phone.
It is very common for users to record programs onto a recording medium to allow later viewing. If the broadcaster uses the same phone numbers for programs broadcasted at different times and viewers do not specify which program they are viewing, confusion may arise when viewers of recorded programs call a phone number that is currently being used for a different program.